Thursday, February 10, 2011

Researchers funded by BBSRC have developed chickens that are genetically modified to prevent them from spreading bird flu to other chickens. If this genetic modification is introduced into poultry flocks in the future it has the potential to protect the health of the birds and so increase the production of meat and eggs. It could also reduce the risk of bird flu epidemics that can lead to new flu outbreaks in the human population.

The study, which the researchers say is the first step in developing chickens that are completely resistant to avian flu, was published last night in the journal Science. The work was carried out by teams based in The Roslin Institute, an institute of BBSRC, at the University of Edinburgh and in the University of Cambridge Department of Veterinary Medicine.

Professor Helen Sang, who led the team at The Roslin Institute said that as well as improving welfare and sustainability in the poultry industry, "this work could also form the basis for improving economic and food security in many regions of the world where bird flu is a significant problem."

Meat production and consumption worldwide is increasing in general and poultry makes up a significant proportion of that increase. There appears to be a trend towards eating chicken as a major source of protein and as the global population is predicted to hit 9 billion in 2050, "infectious diseases of livestock represent a significant threat to global food security," says Professor Douglas Kell, BBSRC Chief Executive.

There is also the potential, Professor Kell added, for infectious diseases of livestock to "jump to humans and become pandemic". This, he says, "has been identified by the Government as a top level national security risk."

Dr Laurence Tiley, Senior Lecturer in Virology who led the team that developed the inhibitory transgene at the University of Cambridge said "Chickens are potential bridging hosts that can enable new strains of flu to be transmitted to humans. Preventing virus transmission in chickens should reduce the risk posed to people exposed to infected birds."

To produce these chickens, the scientists introduced a new gene that manufactures a small "decoy" molecule. In this case, it is a short length of a type of molecule called ribonucleic acid, or RNA. Dr Tiley explained that "the decoy mimics an essential part of the flu virus genome that is identical for all strains of influenza A. The replication machinery of the virus is tricked into recognising the decoy molecule instead of the viral genome and this interferes with the replication cycle of the virus".

The decoy is expected to work against all strains of bird flu and will not need updating for each season.

"The virus will find it difficult to evolve to escape the effects of the decoy. This is quite different from conventional flu vaccines, which need to be updated in the face of virus evolution as they tend only to protect against closely matching strains of virus and do not always prevent spread within a flock," Dr Tiley concluded.